New aluminum alloys having bismuth and/or tin

ABSTRACT

New aluminum alloys having an improved combination of properties are disclosed. In one approach, anew aluminum alloys may include from 0.50 to 3.0 wt. % of X, wherein X comprises (wt. % Bi+wt. % Sn), from 0.50 to 4.0 wt. % Si, from 0.30 to 2.5 wt. % Mg, up to 1.5 wt. % Cu, up to 2.0 wt. % Zn, from 0.05 to 1.5 wt. % Mn, up to 0.70 wt. % Fe, up to 0.35 wt. % of Cr, up to 0.25 wt. % each of Zr and V, and up to 0.15 wt. % Ti, the balance being aluminum, incidental elements and impurities. The new aluminum alloys may comprise at least 0.20 wt. % excess silicon.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of International Patent Application No. PCT/US2021/034082, filed May 25, 2021, which claims benefit of priority of U.S. Provisional Patent Application No. 63/030,155, filed May 26, 2020, both entitled “NEW ALUMINUM ALLOYS HAVING BISMUTH AND/OR TIN,” each of which is incorporated herein by reference in its entirety.

BACKGROUND

Aluminum alloys having, for instance, bismuth, indium, lead and/or tin are known, several of which are described in U.S. Pat. No. 6,409,966. Conventional alloys having bismuth, tin, indium and/or lead include 6020, 6026, and 6262A.

SUMMARY OF THE DISCLOSURE

Broadly, the present patent application relates to new aluminum alloys having an improved combination of at least two of machinability, wear resistance, strength, ductility, corrosion resistance, weldability and fracture toughness. In one approach, a new aluminum alloys may comprise (and in some instances consist essentially of, or consist of), from 0.50 to 3.0 wt. % of X, wherein X comprises (wt. % Bi+wt. % Sn), from 0.50 to 4.0 wt. % Si, from 0.30 to 2.5 wt. % Mg, from 0.25 to 1.5 wt. % Cu, up to 2.0 wt. % Zn, from 0.05 to 1.5 wt. % Mn, up to 0.70 wt. % Fe, up to 0.35 wt. % of Cr, up to 0.25 wt. % each of Zr and V, and up to 0.15 wt. % Ti, the balance being aluminum, optional incidental elements and impurities. The new aluminum alloys may include high amounts of silicon relative to their magnesium content. For instance, the new aluminum alloys may comprise at least 0.20 wt. % excess silicon (defined below). The new aluminum alloys may also comprise high amounts of strengthening precipitates. For instance, the new aluminum alloys may comprise at least 1.75 mol. % of Y, wherein Y is (mol. % Q-phase+mol. % Al₂Cu+mol. % Mg₂Si) as calculated using PANDAT and a temperature of 340° F. (defined below). Other aspects of the new aluminum alloys are described below.

I. Compositions

As noted above, the new aluminum alloys generally comprise from 0.50 to 3.0 wt. % of X, wherein X comprises (wt. % Bi+wt. % Sn). Using appropriate amounts of bismuth and/or tin may facilitate, for instance, machinability of the new aluminum alloys, especially at high temperatures and/or at high machining speeds. In one embodiment, a new aluminum alloy comprises at least 0.60 wt. % of X. In another embodiment, a new aluminum alloy comprises at least 0.70 wt. % of X. In yet another embodiment, a new aluminum alloy comprises at least 0.80 wt. % of X. In another embodiment, a new aluminum alloy comprises at least 0.90 wt. % of X. In yet another embodiment, a new aluminum alloy comprises at least 1.0 wt. % of X. In one embodiment, a new aluminum alloy comprises not greater than 2.5 wt. % of X, wherein X comprises (wt. % Bi+wt. % Sn). In another embodiment, a new aluminum alloy comprises not greater than 2.0 wt. % of X. In yet another embodiment, a new aluminum alloy comprises not greater than 1.50 wt. % of X. In another embodiment, a new aluminum alloy comprises not greater than 1.30 wt. % of X.

In some embodiments, a new aluminum alloy preferentially includes bismuth over tin, i.e., (wt. % Bi)>(wt. % Sn) in the new aluminum alloy. It has been found that the performance of bismuth may exceed that of tin when machining. Furthermore, tin may form the undesired phase of Mg₂Sn with some aluminum alloys and in some machining applications. In one embodiment, bismuth is at least 0.20 wt. % higher than tin, i.e., (wt. % Bi)>(0.2+wt. % Sn) in the new aluminum alloy. In one embodiment, X is bismuth and a new aluminum alloy includes from 0.4 to 1.2 wt. % Bi.

In one embodiment, a new aluminum alloy includes not greater than 1.0 wt. % Sn. In another embodiment, a new aluminum alloy includes not greater than 0.8 wt. % Sn. In yet another embodiment, a new aluminum alloy includes not greater than 0.6 wt. % Sn. In another embodiment, a new aluminum alloy includes not greater than 0.4 wt. % Sn. In yet another embodiment, a new aluminum alloy includes not greater than 0.2 wt. % Sn. In another embodiment, a new aluminum alloy includes not greater than 0.1 wt. % Sn. In yet another embodiment, a new aluminum alloy includes not greater than 0.05 wt. % Sn. In another embodiment, a new aluminum alloy includes not greater than 0.03 wt. % Sn. In yet another embodiment, a new aluminum alloy includes not greater than 0.01 wt. % Sn.

In one embodiment, a new aluminum alloy includes not greater than 0.50 mol. % Mg₂Sn as calculated using PANDAT at 340° F. (as defined below). In another embodiment, a new aluminum alloy includes not greater than 0.45 mol. % Mg₂Sn as calculated using PANDAT at 340° F. In yet another embodiment, a new aluminum alloy includes not greater than 0.40 mol. % Mg₂Sn as calculated using PANDAT at 340° F. In another embodiment, a new aluminum alloy includes not greater than 0.35 mol. % Mg₂Sn as calculated using PANDAT at 340° F. In yet another embodiment, a new aluminum alloy includes not greater than 0.30 mol. % Mg₂Sn as calculated using PANDAT at 340° F. In another embodiment, a new aluminum alloy includes not greater than 0.25 mol. % Mg₂Sn as calculated using PANDAT at 340° F. In yet another embodiment, a new aluminum alloy includes not greater than 0.20 mol. % Mg₂Sn as calculated using PANDAT at 340° F. In another embodiment, a new aluminum alloy includes not greater than 0.15 mol. % Mg₂Sn as calculated using PANDAT at 340° F. In yet another embodiment, a new aluminum alloy includes not greater than 0.10 mol. % Mg₂Sn as calculated using PANDAT at 340° F. In another embodiment, a new aluminum alloy includes not greater than 0.05 mol. % Mg₂Sn as calculated using PANDAT at 340° F. In yet another embodiment, a new aluminum alloy includes 0 (zero) mol. % Mg₂Sn as calculated using PANDAT at 340° F.

In one embodiment, X is selected from the group consisting of Bi, Sn, In, and mixtures thereof. In some embodiments, indium may be used as a partial or complete substitute for bismuth and/or tin. However, indium is expensive and indium may not achieve the machining performance of bismuth and/or tin. In one embodiment, the new aluminum alloys are generally substantially free of indium, i.e., indium is included only as an impurity, and generally at less than 0.04 wt. % In, or less than 0.01 wt. % In. In these embodiments, X is selected from the group consisting of Bi, Sn, and mixtures thereof. In one embodiment, both tin and indium are included in the alloy as impurities only. In these embodiments, X is bismuth.

As noted, the new aluminum alloys generally include from 0.50 to 4.0 wt. % Si and from 0.30 to 2.5 wt. % Mg. The combination of magnesium and silicon facilitates the production of the strengthening precipitate Mg₂Si. In one embodiment, a new aluminum alloy includes at least 0.60 wt. % Si. In another embodiment, a new aluminum alloy includes at least 0.70 wt. % Si. In yet another embodiment, anew aluminum alloy includes at least 0.80 wt. % Si. In another embodiment, a new aluminum alloy includes at least 0.90 wt. % Si. In one embodiment, a new aluminum alloy includes not greater than 3.5 wt. % Si. In another embodiment, a new aluminum alloy includes not greater than 3.0 wt. % Si.

In one embodiment, a new aluminum alloy includes at least 0.40 wt. % Mg. In another embodiment, a new aluminum alloy includes at least 0.50 wt. % Mg. In one embodiment, a new aluminum alloy includes not greater than 2.0 wt. % Mg. In another embodiment, a new aluminum alloy includes not greater than 1.75 wt. % Mg. In yet another embodiment, a new aluminum alloy includes not greater than 1.50 wt. % Mg.

In some instances, the combined content of silicon and magnesium may be controlled. In one approach, a new aluminum alloy includes from 1.2 to 5.0 wt. % Z, wherein Z is (wt. % Si+wt. % Mg). In one embodiment, a new aluminum alloy includes at least 1.3 wt. % Z. In another embodiment, anew aluminum alloy includes at least 1.4 wt. % Z. In yet another embodiment, a new aluminum alloy includes at least 1.5 wt. % Z. In another embodiment, a new aluminum alloy includes at least 1.6 wt. % Z. In yet another embodiment, a new aluminum alloy includes at least 1.7 wt. % Z. In one embodiment, a new aluminum alloy includes not greater than 4.8 wt. % Z, wherein Z is (wt. % Si+wt. % Mg). In another embodiment, a new aluminum alloy not greater than 4.6 wt. % Z. In yet another embodiment, a new aluminum alloy includes not greater than 4.4 wt. % Z. In another embodiment, anew aluminum alloy not greater than 4.3 wt. % Z.

As noted above, the new aluminum alloys may include at least 0.20 wt. % excess silicon (defined below). Using excess silicon may assist with, for instance, improved wear resistance of the material, machinability and/or strength. In one embodiment, a new aluminum alloy includes at least 0.22 wt. % excess silicon. In another embodiment, a new aluminum alloy includes at least 0.24 wt. % excess silicon. In yet another embodiment, a new aluminum alloy includes at least 0.26 wt. % excess silicon. In another embodiment, a new aluminum alloy includes at least 0.28 wt. % excess silicon. In yet another embodiment, a new aluminum alloy includes at least 0.30 wt. % excess silicon. In another embodiment, a new aluminum alloy includes at least 0.40 wt. % excess silicon. In yet another embodiment, a new aluminum alloy includes at least 0.50 wt. % excess silicon. In another embodiment, a new aluminum alloy includes at least 0.60 wt. % excess silicon. In yet another embodiment, a new aluminum alloy includes at least 0.70 wt. % excess silicon.

As noted above, the new aluminum alloys generally include from 0.25 to 1.5 wt. % Cu. Copper may facilitate, for instance, production of Q-phase and Al₂Cu strengthening precipitates. In one embodiment, a new aluminum alloy includes at least 0.30 wt. % Cu. In another embodiment, a new aluminum alloy includes at least 0.35 wt. % Cu. In yet another embodiment, a new aluminum alloy includes at least 0.40 wt. % Cu. In another embodiment, a new aluminum alloy includes at least 0.45 wt. % Cu. In yet another embodiment, a new aluminum alloy includes at least 0.50 wt. % Cu. In one embodiment, a new aluminum alloy includes not greater than 1.4 wt. % Cu. In another embodiment, a new aluminum alloy includes not greater than 1.3 wt. % Cu. In yet another embodiment, a new aluminum alloy includes not greater than 1.2 wt. % Cu. In one embodiment, the amount of copper does not exceed the combined amount of silicon plus magnesium in the new aluminum alloy, i.e., wt. % Cu≤(wt. % Si+wt. % Mg). In one embodiment, the amount of copper does not exceed the amount of silicon in the new aluminum alloy, i.e., wt. % Cu≤wt. % Si. In one embodiment, the amount of copper does not exceed the amount of magnesium in the new aluminum alloy, i.e., wt. % Cu≤wt. % Mg. In one embodiment, the amount of copper is less than both the amount of silicon and the amount of magnesium in the new aluminum alloy, i.e., wt. % Cu≤wt. % Si and wt. % Cu≤wt. % Mg.

As noted above, due to, for instance, the silicon, magnesium and copper content, a new aluminum alloy may include high amounts of strengthening precipitates. In one embodiment, a new aluminum alloy may comprise at least 1.75 mol. % of Y, wherein Y is (mol. % Q-phase+mol. % Al₂Cu+mol. % Mg₂Si) as calculated using PANDAT and a temperature of 340° F. (defined below). In another embodiment, a new aluminum alloy includes at least 1.85 mol. % of Y. In yet another embodiment, a new aluminum alloy includes at least 1.9 mol. % of Y. In another embodiment, a new aluminum alloy includes at least 1.95 mol. % of Y. In yet another embodiment, a new aluminum alloy includes at least 2.0 mol. % of Y. In another embodiment, a new aluminum alloy includes at least 2.05 mol. % of Y. In yet another embodiment, a new aluminum alloy includes at least 2.1 mol. % of Y. In another embodiment, a new aluminum alloy includes at least 2.15 mol. % of Y. In yet another embodiment, a new aluminum alloy includes at least 2.2 mol. % of Y.

As noted about, the new aluminum alloys may include up to 2.0 wt. % Zn. Zinc may facilitate, for instance, improved work hardening and/or corrosion resistance. In one embodiment, a new aluminum alloy includes at least 0.05 wt. % Zn. In another embodiment, a new aluminum alloy includes at least 0.10 wt. % Zn. In yet another embodiment, a new aluminum alloy includes at least 0.15 wt. % Zn. In another embodiment, a new aluminum alloy includes at least 0.20 wt. % Zn. In yet another embodiment, a new aluminum alloy includes at least 0.30 wt. % Zn. In another embodiment, a new aluminum alloy includes at least 0.40 wt. % Zn. In yet another embodiment, a new aluminum alloy includes at least 0.50 wt. % Zn. In another embodiment, a new aluminum alloy includes at least 0.60 wt. % Zn. In yet another embodiment, a new aluminum alloy includes at least 0.70 wt. % Zn. In one embodiment, a new aluminum alloy includes not greater than 1.5 wt. % Zn. In another embodiment, a new aluminum alloy includes not greater than 1.0 wt. % Zn.

In one embodiment, a new aluminum alloy includes both high amounts of excess silicon plus high amounts of solute to facilitate, for instance, improved wear resistance, high strength and/or corrosion resistance. In one embodiment, a new aluminum alloy includes an amount of excess silicon multiplied by the combined amount of copper and zinc that achieves a value of 0.10, i.e., (wt. % excess silicon) X (wt. % Cu+wt. % Zn) is at least 0.10. In another embodiment, the amount of excess silicon multiplied by the combined amount of copper and zinc achieves a value of 0.15, i.e., (wt. % excess silicon) X (wt. % Cu+wt. % Zn) is at least 0.15. In yet another embodiment, the amount of excess silicon multiplied by the combined amount of copper and zinc achieves a value of 0.20, i.e., (wt. % excess silicon) X (wt. % Cu+wt. % Zn) is at least 0.20. In another embodiment, the amount of excess silicon multiplied by the combined amount of copper and zinc achieves a value of 0.25, i.e., (wt. % excess silicon) X (wt. % Cu+wt. % Zn) is at least 0.25. In yet another embodiment, the amount of excess silicon multiplied by the combined amount of copper and zinc achieves a value of 0.30, i.e., (wt. % excess silicon) X (wt. % Cu+wt. % Zn) is at least 0.30. In another embodiment, the amount of excess silicon multiplied by the combined amount of copper and zinc achieves a value of 0.35, i.e., (wt. % excess silicon) X (wt. % Cu+wt. % Zn) is at least 0.35. In yet another embodiment, the amount of excess silicon multiplied by the combined amount of copper and zinc achieves a value of 0.40, i.e., (wt. % excess silicon) X (wt. % Cu+wt. % Zn) is at least 0.40. In another embodiment, the amount of excess silicon multiplied by the combined amount of copper and zinc achieves a value of 0.45, i.e., (wt. % excess silicon) X (wt. % Cu+wt. % Zn) is at least 0.45. In yet another embodiment, the amount of excess silicon multiplied by the combined amount of copper and zinc achieves a value of 0.50, i.e., (wt. % excess silicon) X (wt. % Cu+wt. % Zn) is at least 0.50. In another embodiment, the amount of excess silicon multiplied by the combined amount of copper and zinc achieves a value of 0.60, i.e., (wt. % excess silicon) X (wt. % Cu+wt. % Zn) is at least 0.60. In yet another embodiment, the amount of excess silicon multiplied by the combined amount of copper and zinc achieves a value of 0.70, i.e., (wt. % excess silicon) X (wt. % Cu+wt. % Zn) is at least 0.70. In another embodiment, the amount of excess silicon multiplied by the combined amount of copper and zinc achieves a value of 0.80, i.e., (wt. % excess silicon) X (wt. % Cu+wt. % Zn) is at least 0.80.

As noted above, the new aluminum alloys generally include from 0.05 to 1.5 wt. % Mn. Manganese may facilitate, for instance, proper grain structure control. In one embodiment, a new aluminum alloy includes at least 0.08 wt. % Mn. In another embodiment, a new aluminum alloy includes at least 0.10 wt. % Mn. In yet another embodiment, a new aluminum alloy includes at least 0.12 wt. % Mn. In another embodiment, a new aluminum alloy includes at least 0.15 wt. % Mn. In one embodiment, a new aluminum alloy includes not greater than 1.25 wt. % Mn. In another embodiment, a new aluminum alloy includes not greater than 1.0 wt. % Mn. In yet another embodiment, a new aluminum alloy includes not greater than 0.90 wt. % Mn. In another embodiment, a new aluminum alloy includes not greater than 0.80 wt. % Mn. In yet another embodiment, a new aluminum alloy includes not greater than 0.70 wt. % Mn. In another embodiment, a new aluminum alloy includes not greater than 0.65 wt. % Mn. In yet another embodiment, a new aluminum alloy includes not greater than 0.60 wt. % Mn. In another embodiment, a new aluminum alloy includes not greater than 0.55 wt. % Mn. In yet another embodiment, a new aluminum alloy includes not greater than 0.50 wt. % Mn. In another embodiment, a new aluminum alloy includes not greater than 0.45 wt. % Mn. In yet another embodiment, a new aluminum alloy includes not greater than 0.40 wt. % Mn.

As noted above, a new aluminum alloy may include up to 0.70 wt. % Fe. Iron is a normal impurity in primary aluminum. In one embodiment, a new aluminum alloy includes at least 0.05 wt. % Fe. In another embodiment, a new aluminum alloy includes at least 0.10 wt. % Fe. In yet another embodiment, a new aluminum alloy includes at least 0.15 wt. % Fe. In another embodiment, a new aluminum alloy includes at least 0.20 wt. % Fe. In one embodiment, a new aluminum alloy includes not greater than 0.6 wt. % Fe. In another embodiment, a new aluminum alloy includes not greater than 0.5 wt. % Fe. In yet another embodiment, a new aluminum alloy includes not greater than 0.45 wt. % Fe.

As noted above, a new aluminum alloy may include up to 0.35 wt. % Cr and up to 0.25 wt. % each of Zr and V. These elements may facilitate, for instance, grain structure control. In one embodiment, at least one of Cr, Zr, and V is included in a new aluminum alloy, wherein a new aluminum alloy includes at least 0.05 wt. % of at least one of Cr, V and Z. In one embodiment, the element is chromium, and a new aluminum alloy includes at least 0.05 wt. % Cr. In another embodiment, a new aluminum alloy includes at least 0.10 wt. % Cr. In one embodiment, a new aluminum alloy includes not greater than 0.30 wt. % Cr. In another embodiment, a new aluminum alloy includes not greater than 0.25 wt. % Cr. In some embodiments, it is preferred to restrict zirconium and/or vanadium in favor of chromium. In one embodiment, a new aluminum alloy includes not greater than 0.05 wt. % Zr or not greater than 0.03 wt. % Zr. In one embodiment, a new aluminum alloy includes not greater than 0.05 wt. % V or not greater than 0.03 wt. % V. In one embodiment, an aluminum alloy is substantially free of chromium, containing less than 0.04 wt. % Cr.

As noted above, a new aluminum alloy may include up to 0.15 wt. % Ti. Titanium may facilitate, for instance, grain refining. In one embodiment, a new aluminum alloy includes at least 0.02 wt. % Ti. In another embodiment, a new aluminum alloy includes at least 0.04 wt. % Ti. In one embodiment, a new aluminum alloy includes not greater than 0.12 wt. % Ti. In another embodiment, a new aluminum alloy includes not greater than 0.10 wt. % Ti.

As noted above, the new aluminum alloys generally include the stated alloying ingredients, the balance being aluminum, optional incidental elements, and impurities. As used herein, “incidental elements” means those elements or materials, other than the above listed elements, that may optionally be added to the alloy to assist in the production of the alloy. Examples of incidental elements include casting aids, such as grain refiners and deoxidizers. Optional incidental elements may be included in the alloy in a cumulative amount of up to 1.0 wt. %. As one non-limiting example, one or more incidental elements may be added to the alloy during casting to reduce or restrict (and in some instances eliminate) ingot cracking due to, for example, oxide fold, pit and oxide patches. These types of incidental elements are generally referred to herein as deoxidizers. Examples of some deoxidizers include Ca, Sr, and Be. When calcium (Ca) is included in the alloy, it is generally present in an amount of up to about 0.05 wt. %, or up to about 0.03 wt. %. In some embodiments, Ca is included in the alloy in an amount of about 0.001-0.03 wt % or about 0.05 wt. %, such as 0.001-0.008 wt. % (or 10 to 80 ppm). Traditionally, beryllium (Be) additions have helped to reduce the tendency of ingot cracking, though for environmental, health and safety reasons, some embodiments of the alloy are substantially Be-free. When Be is included in the alloy, it is generally present in an amount of up to about 20 ppm. Incidental elements may be present in minor amounts, or may be present in significant amounts, and may add desirable or other characteristics on their own without departing from the alloy described herein, so long as the alloy retains the desirable characteristics described herein. It is to be understood, however, that the scope of this disclosure should not/cannot be avoided through the mere addition of an element or elements in quantities that would not otherwise impact on the combinations of properties desired and attained herein.

In one embodiment, the new aluminum alloys include strontium as an optional incidental element. Strontium may facilitate, for instance, improved machinability. In one approach, a new aluminum alloy includes from 10 to 500 ppm strontium. In one embodiment, a new aluminum alloy includes at least 50 ppm strontium. In another embodiment, a new aluminum alloy includes at least 100 ppm strontium. In one embodiment, a new aluminum alloy includes not greater than 400 ppm strontium. In another embodiment, a new aluminum alloy includes not greater than 300 ppm strontium. In one embodiment, a new aluminum alloy includes from 100 to 300 ppm of strontium.

In another approach, a new aluminum alloy includes strontium as an impurity. In one embodiment, a new aluminum alloy includes not greater than 10 ppm Sr. In another embodiment, a new aluminum alloy includes not greater than 5 ppm Sr. In yet another embodiment, a new aluminum alloy includes not greater than 1 ppm Sr, or less.

The new aluminum alloys may contain low amounts of impurities. In one embodiment, a new aluminum alloy includes not greater than 0.15 wt. %, in total, of the impurities, and wherein the aluminum alloy includes not greater than 0.05 wt. % of each of the impurities. In another embodiment, a new aluminum alloy includes not greater than 0.10 wt. %, in total, of the impurities, and wherein the aluminum alloy includes not greater than 0.03 wt. % of each of the impurities.

The new aluminum alloys are generally substantially free of lithium, i.e., lithium is included only as an impurity, and generally at less than 0.04 wt. % Li, or less than 0.01 wt. % Li. The new aluminum alloys are generally substantially free of silver, i.e., silver is included only as an impurity, and generally at less than 0.04 wt. % Ag, or less than 0.01 wt. % Ag. The new aluminum alloys are generally substantially free of lead, i.e., lead is included only as an impurity, and generally at less than 0.04 wt. % Pb, or less than 0.01 wt. % Pb. The new aluminum alloys are generally substantially free of cadmium, i.e., cadmium is included only as an impurity, and generally at less than 0.04 wt. % Cd, or less than 0.01 wt. % Cd. The new aluminum alloys are generally substantially free of thallium, i.e., thallium is included only as an impurity, and generally at less than 0.04 wt. % Tl, or less than 0.01 wt. % Tl. The new aluminum alloys are generally substantially free of scandium, i.e., scandium is included only as an impurity, and generally at less than 0.04 wt. % Sc, or less than 0.01 wt. % Sc.

In one approach, a new aluminum alloy has a composition consistent with attributes of Example alloys 7-8, below. In this approach, a new aluminum alloy may include 0.65-1.15 wt. % X, wherein X is selected from the group consisting of Bi, Sn, In, and combinations thereof, 0.95-1.3 wt. % Si, 0.45-0.70 wt. % Mg, 1.0-1.4 wt. % Cu, from 0.30 to 0.85 wt. % excess silicon, optionally with (Excess-Si) x (Cu+Zn) being at least 0.30, amounts of Fe, Mn, Cr, Zr, V, and Ti as per above, the balance being aluminum, optional incidental elements and impurities. In one embodiment, such an alloy comprises at least 2.0 mol. % of Y, wherein Y is (mol. % Q-phase+mol. % Al₂Cu+mol. % Mg₂Si) as calculated using PANDAT and a temperature of 340° F. (defined below). In one embodiment, such an alloy comprises zinc as an impurity. In one embodiment, such an alloy comprises vanadium and zirconium as impurities. In one embodiment, such an alloy comprises bismuth as X, and tin and indium are impurities.

In one approach, a new aluminum alloy has a composition consistent with attributes of Example alloy 9, below. In this approach, a new aluminum alloy may include 0.85-1.4 wt. % X, wherein X is selected from the group consisting of Bi, Sn, In, and combinations thereof, 0.80-1.1 wt. % Si, 0.75-1.05 wt. % Mg, 0.5-1.5 wt. % Cu, 0.5-1.5 wt. % Zn, from 0.22 to 0.35 wt. % excess silicon, optionally with (Excess-Si) x (Cu+Zn) being at least 0.30, amounts of Fe, Mn, Cr, Zr, V, and Ti as per above, the balance being aluminum, optional incidental elements and impurities. In one embodiment, such an alloy comprises at least 2.0 mol. % of Y, wherein Y is (mol. % Q-phase+mol. % Al₂Cu+mol. % Mg₂Si) as calculated using PANDAT and a temperature of 340° F. (defined below). In one embodiment, such an alloy comprises from 0.6-1.0 wt. % Zn. In one embodiment, such an alloy comprises vanadium and zirconium as impurities. In one embodiment, such an alloy comprises bismuth as X, and tin and indium are impurities.

In one approach, a new aluminum alloy has a composition consistent with attributes of Example alloy 11, below. In this approach, a new aluminum alloy may include 0.5-1.4 wt. % X, wherein X is selected from the group consisting of Bi, Sn, In, and combinations thereof, 2.2-3.5 wt. % Si, 1.1-2.5 wt. % Mg, up to 1.5 wt. % Cu, up to 2.0 wt. % Zn, up to 0.7 wt. % Fe, up to 1.5 wt. % Mn, up to 0.35 wt. % Cr, up to 0.25 wt. % each of Zr and V, up to 0.15 wt. % Ti, from 0.5 to 2.3 wt. % excess silicon, optionally with (Excess-Si) x (Cu+Zn) being at least 0.30, the balance being aluminum, optional incidental elements and impurities. In one embodiment, such an alloy comprises at least 2.0 mol. % of Y, wherein Y is (mol. % Q-phase+mol. % Al₂Cu+mol. % Mg₂Si) as calculated using PANDAT and a temperature of 340° F. (defined below). In one embodiment, such an alloy comprises from 0.25 to 1.0 wt. % Cu. In one embodiment, such an alloy comprises from 0.25 to 1.0 wt. % Zn. In one embodiment, such an alloy comprises from 0.1-1.0 wt. % Mn. In one embodiment, such an alloy comprises from 0.15 to 0.50 wt. % Fe. In one embodiment, such an alloy comprises from 0.05 to 0.25 wt. % Cr. In one embodiment, such an alloy comprises vanadium and zirconium as impurities. In one embodiment, such an alloy comprises bismuth as X, and tin and indium are impurities.

II. Methods of Production

The new aluminum alloys may be useful in a variety of product forms, including ingot or billet, wrought product forms (plate, forgings and extrusions), shape castings, additively manufactured products, and powder metallurgy products, for instance. For instance, the new aluminum alloys may be processed into a variety of wrought forms, such as in rolled form (sheet, plate), as an extrusion, or as a forging, and in a variety of tempers. In this regard, the new aluminum alloys may be cast (e.g., direct chill cast or continuously cast) into an ingot, billet, or strip. In one embodiment, a method includes casting an ingot (or billet) of any of the aluminum alloys described in Section I, above, followed by homogenization, scalping, lathing or peeling (if needed). After casting, the ingot/billet/strip may be worked (hot and/or cold worked) into the appropriate product form (sheet, plate, extrusion, or forging). After working, the new aluminum alloys may be processed to one of a T temper, a W temper, or an F temper as per ANSI H35.1 (2009). In one embodiment, a new aluminum alloy is processed to a “T temper” (thermally treated). In this regard, the new aluminum alloys may be processed to any of a T1, T2, T3, T4, T5, T6, T7, T8, T9 or T10 temper as per ANSI H35.1 (2009).

In one embodiment, the new aluminum alloys are processed to one of a T6, T8, or T9 temper from an ingot or billet, wherein the ingot/billet is hot worked and optionally cold worked to an intermediate of final product form prior to solution heat treatment. When processing to a T6 temper, the hot working and optional cold working result in the product being at final gauge prior to solution heat treatment. When processing to a T8 or T9 temper, the hot working and optional cold working result in the product being at an intermediate gauge prior to solution heat treatment. For any of the T6, T8 or T9 tempers, after the hot working and any optional cold working, the product may be solution heat treated and then quenched (e.g., cold water quenched; air quenched). When processing to a T6 temper, the solution heat treated product, which is already at final gauge, is artificially aged. When processing to a T8 temper, the solution heat treated product is cold worked to final gauge and then artificially aged. When processing to a T9 temper, the solution heat treated product is artificially aged and then cold worked to final gauge.

In another embodiment, the new aluminum alloys are processed to one of a T5 or T10 temper from an ingot or billet. T5 tempering involves the same general processing as T6 except that solution heat treatment and quenching is completed as press quenching. Similarly, T10 tempering involves the same general processing as T8 except that solution heat treatment and quenching is completed as press quenching.

In one embodiment, the new aluminum alloy product is an extrusion. In one embodiment, the extrusion is in the form of a rod, tube, wire, bar (e.g., square, rectangular, hexagonal) or other extruded profiles. In one embodiment, the extruded product is processed to a T5 temper. In another embodiment, the extruded product is processed to a T6 temper. In another embodiment, the extruded product is processed to a T8 temper. In yet another embodiment, the extruded product is processed to a T9 temper. In another embodiment, the extruded product is processed to a T10 temper. In one embodiment, the cold working after the solution heat treatment (whether for the T8/T10 or the T9 temper) includes, for instance, drawing.

III. Properties

As noted above, the new aluminum alloys may realize an improved combination of properties, such as an improved combination of two or more of machinability, wear resistance, strength, ductility, corrosion resistance, weldability, and fracture toughness.

In one embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 46 ksi in the T6 temper. In another embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 47 ksi in the T6 temper. In yet another embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 48 ksi in the T6 temper. In another embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 49 ksi in the T6 temper. In yet another embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 50 ksi in the T6 temper. In another embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 51 ksi in the T6 temper. In any of these embodiments, the new aluminum alloy may realize an elongation of at least 10%, or at least 11%, or at least 12%, or at least 13%, or at least 14%, or at least 15%, or at least 16%, or at least 17%, or higher. Similar properties may be realized in the T5 temper.

In one embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 50 ksi in the T8 temper. In another embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 51 ksi in the T8 temper. In yet another embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 52 ksi in the T8 temper. In another embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 53 ksi in the T8 temper. In yet another embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 54 ksi in the T8 temper. In another embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 55 ksi in the T8 temper. In any of these embodiments, the new aluminum alloy may realize an elongation of at least 6%, or at least 7%, or at least 8%, or at least 9%, or at least 10%, or at least 11%, or at least 12%, or higher. Similar properties may be realized in the T10 temper.

In one embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 54 ksi in the T9 temper. In another embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 55 ksi in the T9 temper. In yet another embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 56 ksi in the T9 temper. In another embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 57 ksi in the T9 temper. In yet another embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 58 ksi in the T9 temper. In another embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 59 ksi in the T9 temper. In yet another embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 60 ksi in the T9 temper. In another embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 61 ksi in the T9 temper. In yet another embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 62 ksi in the T9 temper. In another embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 63 ksi in the T9 temper. In yet another embodiment, a new aluminum alloy realizes a longitudinal tensile yield strength (typical) of at least 64 ksi in the T9 temper. In any of these embodiments, the new aluminum alloy may realize an elongation of at least 3%, or at least 4%, or at least 5%, or at least 6%, or at least 7%, or at least 8%, or higher.

In one embodiment, a new aluminum alloy realizes a machinability rating equivalent to that of 6020 in the same product form and temper. In another embodiment, a new aluminum alloy realizes a machinability rating equivalent to that of 6262A in the same product form and temper. In another embodiment, a new aluminum alloy realizes a machinability rating equivalent to that of 6026LF in the same product form and temper. In one embodiment, a new aluminum alloy realizes improved tool life, wherein the life of the machining tools is good to excellent.

In one embodiment, a new aluminum alloy in the T6 temper realizes at least 5% higher strength as compared to one or more of a 6026LF alloy, a 6262A alloy, and a 6020 alloy of equivalent product form and temper. In another embodiment, a new aluminum alloy in the T6 temper realizes at least 7.5% higher strength as compared to one or more of a 6026LF alloy, a 6262A alloy, and a 6020 alloy of equivalent product form and temper. In another embodiment, a new aluminum alloy in the T6 temper realizes at least 10% higher strength as compared to one or more of a 6026LF alloy, a 6262A alloy, and a 6020 alloy of equivalent product form and temper. In another embodiment, a new aluminum alloy in the T6 temper realizes at least 12.5% higher strength as compared to one or more of a 6026LF alloy, a 6262A alloy, and a 6020 alloy of equivalent product form and temper. In another embodiment, a new aluminum alloy in the T6 temper realizes at least 15% higher strength as compared to one or more of a 6026LF alloy, a 6262A alloy, and a 6020 alloy of equivalent product form and temper. In another embodiment, a new aluminum alloy in the T6 temper realizes at least 17.5% higher strength as compared to one or more of a 6026LF alloy, a 6262A alloy, and a 6020 alloy of equivalent product form and temper. In another embodiment, a new aluminum alloy in the T6 temper realizes at least 20% higher strength as compared to one or more of a 6026LF alloy, a 6262A alloy, and a 6020 alloy of equivalent product form and temper. In any of these embodiments, the new aluminum alloy may realize an elongation of at least 10%, or at least 11%, or at least 12%, or at least 13%, or at least 14%, or at least 15%, or at least 16%, or at least 17%, or higher. In any of these embodiments, the new aluminum alloy may realize the same or better machinability as compared to one or more of the 6026LF alloy, the 6262A alloy, and the 6020 alloy of equivalent product form and temper.

In one embodiment, a new aluminum alloy in the T8 temper realizes at least 5% higher strength as compared to one or more of a 6026LF alloy, a 6262A alloy, and a 6020 alloy of equivalent product form and temper. In another embodiment, a new aluminum alloy in the T8 temper realizes at least 7.5% higher strength as compared to one or more of a 6026LF alloy, a 6262A alloy, and a 6020 alloy of equivalent product form and temper. In another embodiment, a new aluminum alloy in the T8 temper realizes at least 10% higher strength as compared to one or more of a 6026LF alloy, a 6262A alloy, and a 6020 alloy of equivalent product form and temper. In another embodiment, a new aluminum alloy in the T8 temper realizes at least 12.5% higher strength as compared to one or more of a 6026LF alloy, a 6262A alloy, and a 6020 alloy of equivalent product form and temper. In another embodiment, a new aluminum alloy in the T8 temper realizes at least 15% higher strength as compared to one or more of a 6026LF alloy, a 6262A alloy, and a 6020 alloy of equivalent product form and temper. In another embodiment, a new aluminum alloy in the T8 temper realizes at least 17.5% higher strength as compared to one or more of a 6026LF alloy, a 6262A alloy, and a 6020 alloy of equivalent product form and temper. In another embodiment, a new aluminum alloy in the T8 temper realizes at least 20% higher strength as compared to one or more of a 6026LF alloy, a 6262A alloy, and a 6020 alloy of equivalent product form and temper. In any of these embodiments, the new aluminum alloy may realize an elongation of at least 6%, or at least 7%, or at least 8%, or at least 9%, or at least 10%, or at least 11%, or at least 12%, or higher. In any of these embodiments, the new aluminum alloy may realize the same or better machinability as compared to one or more of the 6026LF alloy, the 6262A alloy, and the 6020 alloy of equivalent product form and temper.

In one embodiment, a new aluminum alloy in the T9 temper realizes at least 5% higher strength as compared to one or more of a 6026LF alloy, a 6262A alloy, and a 6020 alloy of equivalent product form and temper. In another embodiment, a new aluminum alloy in the T9 temper realizes at least 7.5% higher strength as compared to one or more of a 6026LF alloy, a 6262A alloy, and a 6020 alloy of equivalent product form and temper. In another embodiment, a new aluminum alloy in the T9 temper realizes at least 10% higher strength as compared to one or more of a 6026LF alloy, a 6262A alloy, and a 6020 alloy of equivalent product form and temper. In another embodiment, a new aluminum alloy in the T9 temper realizes at least 12.5% higher strength as compared to one or more of a 6026LF alloy, a 6262A alloy, and a 6020 alloy of equivalent product form and temper. In another embodiment, a new aluminum alloy in the T9 temper realizes at least 15% higher strength as compared to one or more of a 6026LF alloy, a 6262A alloy, and a 6020 alloy of equivalent product form and temper. In another embodiment, a new aluminum alloy in the T9 temper realizes at least 17.5% higher strength as compared to one or more of a 6026LF alloy, a 6262A alloy, and a 6020 alloy of equivalent product form and temper. In another embodiment, a new aluminum alloy in the T9 temper realizes at least 20% higher strength as compared to one or more of a 6026LF alloy, a 6262A alloy, and a 6020 alloy of equivalent product form and temper. In any of these embodiments, the new aluminum alloy may realize an elongation of at least 3%, or at least 4%, or at least 5%, or at least 6%, or at least 7%, or at least 8%, or higher. In any of these embodiments, the new aluminum alloy may realize the same or better machinability as compared to one or more of the 6026LF alloy, the 6262A alloy, and the 6020 alloy of equivalent product form and temper.

In one embodiment, a new 6xxx aluminum alloy achieves at least the same chips-per-mass results as a conventional alloy 6026LF, 6262A or 6020 aluminum alloy for a given Machinability Condition and temper. In one embodiment, a new 6xxx aluminum alloy achieves at least 10% more chips-per-mass results as conventional alloy 6026LF, 6262A and/or 6020 aluminum alloy for a given Machinability Condition and temper. In another embodiment, a new 6xxx aluminum alloy achieves at least 20% more chips-per-mass results as conventional alloy 6026LF, 6262A and/or 6020 aluminum alloy for a given Machinability Condition and temper. In yet another embodiment, a new 6xxx aluminum alloy achieves at least 30% more chips-per-mass results as conventional alloy 6026LF, 6262A and/or 6020 aluminum alloy for a given Machinability Condition and temper. In another embodiment, a new 6xxx aluminum alloy achieves at least 40% more chips-per-mass results as conventional alloy 6026LF, 6262A and/or 6020 aluminum alloy for a given Machinability Condition and temper. In yet another embodiment, a new 6xxx aluminum alloy achieves at least 50% more chips-per-mass results as conventional alloy 6026LF, 6262A and/or 6020 aluminum alloy for a given Machinability Condition and temper. In another embodiment, a new 6xxx aluminum alloy achieves at least 60% more, or more, same chips-per-mass results as conventional alloy 6026LF, 6262A and/or 6020 aluminum alloy for a given Machinability Condition and temper. In yet another embodiment, a new 6xxx aluminum alloy achieves at least 70% more chips-per-mass results as conventional alloy 6026LF, 6262A and/or 6020 aluminum alloy for a given Machinability Condition and temper. In another embodiment, a new 6xxx aluminum alloy achieves at least 80% more, or more, same chips-per-mass results as conventional alloy 6026LF, 6262A and/or 6020 aluminum alloy for a given Machinability Condition and temper. In yet another embodiment, a new 6xxx aluminum alloy achieves at least 90% more chips-per-mass results as conventional alloy 6026LF, 6262A and/or 6020 aluminum alloy for a given Machinability Condition and temper. In another embodiment, a new 6xxx aluminum alloy achieves at least 100% more, or more, same chips-per-mass results as conventional alloy 6026LF, 6262A and/or 6020 aluminum alloy for a given Machinability Condition and temper. In one approach, the Machinability Condition for any of the above embodiments is Machinability Condition No. 1 (defined in Example 2, below). In another approach, the Machinability Condition for any of the above embodiments is Machinability Condition No. 2. In yet another approach, the Machinability Condition for any of the above embodiments is Machinability Condition No. 3. In another approach, the Machinability Condition for any of the above embodiments is Machinability Condition No. 4. In yet another approach, the Machinability Condition for any of the above embodiments is Machinability Condition No. 5. In another approach, the Machinability Condition for any of the above embodiments is Machinability Condition No. 6.

In one embodiment, a new aluminum alloy is weldable. In one embodiment, a new aluminum alloy is arc weldable.

IV. Product Applications

The new aluminum alloys described herein may be used in a variety of product applications, such as in automotive and/or aerospace applications. For instance, in extruded form, the new alloys may be used as transmission valves or electrical connector fittings, among others.

V. Definitions

As used herein, the phrase “as calculated using PANDAT at a temperature of 340° F.,” means using the PANDAT computer program employing the PanAluminum database, wherein the PANDAT computer program determines (outputs) the molar percentages of precipitate(s) of the specified items at a temperature of 340° F., and with any Al₃Cu₅Zn₂ phases suspended. The PANDAT software and the PanAluminum database are available from Computherm, LLC, 8401 Greenway Blvd, Suite 248, Middleton, Wis. 53562, USA (www.computherm.com).

As used herein, “excess silicon” is to be calculated from the formula: (Si−(Fe*0.333))−(Mg/1.73), wherein the values of silicon, iron, and magnesium are the weight percent of those elements in the new aluminum alloy. For instance, an alloy with 1.2 wt. % Si, 1.0 wt. % Mg, and 0.30 wt. % Fe has an excess silicon content of (1.2−(0.30*0.333))−(1.0/1.73) or 0.52 wt. % excess silicon. The value of 1.73 represents the weight ratio of magnesium to silicon in magnesium silicide (Mg₂Si).

“Wrought aluminum alloy product” means an aluminum alloy product that is hot worked after casting, and includes rolled products (sheet or plate), forged products, and extruded products.

“Forged aluminum alloy product” means a wrought aluminum alloy product that is either die forged or hand forged.

“Hot working” means working the aluminum alloy product at elevated temperature, generally at least 250° F. Strain-hardening is restricted/avoided during hot working, which generally differentiates hot working from cold working.

“Cold working” means working the aluminum alloy product at temperatures that are not considered hot working temperatures, generally below about 250° F. (e.g., at ambient).

Strength and elongation are measured in accordance with ASTM E8 and B557.

Temper definitions are per ANSI H35.1 (2009), entitled “American National Standard Alloy and Temper Designation Systems for Aluminum,” published by The Aluminum Association.

The compositions of the conventional 6020, 6026, and 6262A alloys described herein are per the Aluminum Association document entitled “International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys” (2015).

The “6026LF” alloy is defined as a lead-free version of the 6026 alloy, and includes 0.6-0-1.40 wt. % Si, ≤0.70 wt. % Fe, 0.20-0.50 wt. % Cu, 0.20-1.00 wt. % Mn, 0.60-1.20 wt. % Mg, ≤0.30 wt. % Cr, ≤0.30 wt. % Zn, ≤0.20 wt. % Ti, ≤0.05 wt. % Sn, ≤0.05 wt. % Pb, and 0.50-1.50 wt. % Bi, the balance being aluminum and impurities.

As used herein, “additive manufacturing” means “a process of joining materials to make objects from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing methodologies”, as defined in ASTM F2792-12a entitled “Standard Terminology for Additively Manufacturing Technologies.” Non-limiting examples of additive manufacturing processes useful in producing aluminum alloy products include, for instance, DMLS (direct metal laser sintering), SLM (selective laser melting), SLS (selective laser sintering), and EBM (electron beam melting), among others. Any suitable feedstocks made from the above new aluminum alloys may be used, including one or more powders, one or more wires, one or more sheets, and combinations thereof. In some embodiments the additive manufacturing feedstock is comprised of one or more powders comprising the new aluminum alloys. Shavings are types of particles. In some embodiments, the additive manufacturing feedstock is comprised of one or more wires comprising the new aluminum alloys. A ribbon is a type of wire. In some embodiments, the additive manufacturing feedstock is comprised of one or more sheets comprising the new aluminum alloys. Foil is a type of sheet.

VI. Miscellaneous

These and other aspects, advantages, and novel features of this new technology are set forth in part in the description that follows and will become apparent to those skilled in the art upon examination of the following description and figures or may be learned by practicing one or more embodiments of the technology provided for by the present disclosure.

The figures constitute a part of this specification and include illustrative embodiments of the present disclosure and illustrate various objects and features thereof. In addition, any measurements, specifications and the like shown in the figures are intended to be illustrative, and not restrictive. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.

Among those benefits and improvements that have been disclosed, other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying figures. Detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely illustrative of the invention that may be embodied in various forms. In addition, each of the examples given in connection with the various embodiments of the invention is intended to be illustrative, and not restrictive.

Throughout the specification and claims, the following terms take the meanings explicitly associated herein, unless the context clearly dictates otherwise. The phrases “in one embodiment” and “in some embodiments” as used herein do not necessarily refer to the same embodiment(s), though they may. Furthermore, the phrases “in another embodiment” and “in some other embodiments” as used herein do not necessarily refer to a different embodiment, although they may. Thus, various embodiments of the invention may be readily combined, without departing from the scope or spirit of the invention.

In addition, as used herein, the term “or” is an inclusive “or” operator and is equivalent to the term “and/or,” unless the context clearly dictates otherwise. The term “based on” is not exclusive and allows for being based on additional factors not described, unless the context clearly dictates otherwise. In addition, throughout the specification, the meaning of “a,” “an,” and “the” include plural references, unless the context clearly dictates otherwise. The meaning of “in” includes “in” and “on”, unless the context clearly dictates otherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph illustrating the excess silicon content or excess magnesium content of the Example 1 alloys.

FIG. 2 is a graph illustrating machinability results for Example 2 alloys in the T8 temper.

FIG. 3 is a graph illustrating machinability results for Example 2 alloys in the T9 temper.

FIG. 4 is a graph illustrating wear resistance results for Example 2 alloys in the bare (unanodized) condition.

FIG. 5 is a graph illustrating wear resistance results for Example 2 alloys in the anodized condition.

FIG. 6 is a schematic view illustrating “Feed/Rev” per Example 2.

DETAILED DESCRIPTION Example 1—Book Mold Study

Eleven book mold ingots were produced, the compositions of which are provided in Table 1, below (all values in weight percent).

TABLE 1 Example 1 Alloy Compositions* Alloy Si Fe Cu Mn Mg Cr Zn Ti Sn Bi 1 0.77 0.44 0.45 0.56 0.74 0.07 — 0.06 — 0.98 2 0.72 0.48 0.32 0.13 0.89 0.13 — 0.03 0.77 0.59 3 0.56 0.39 0.61 — 1.00 0.02 — 0.07 1.01 — 4 0.72 0.49 0.33 — 0.87 0.06 — 0.03 0.83 0.56 5 0.87 0.53 0.44 0.08 0.98 0.24 0.13 0.05 — 0.96 6 0.92 0.62 0.46 0.15 0.98 0.27 — 0.04 — 1.04 7 1.12 0.20 1.18 0.45 0.60 0.11 — 0.05 — 1.00 8 1.14 0.26 1.19 0.54 0.57 0.10 — 0.05 0.37 0.40 9 0.95 0.44 0.82 0.11 0.90 0.25 0.74 0.08 0.60 0.61 10 0.62 0.51 0.75 — 1.02 0.09 — 0.05 — 1.12 11 2.91 0.32 0.42 0.16 1.38 0.12 — 0.10 — 1.00 *All alloys contained the listed elements, the balance being aluminum and other impurities, where the other impurities did not exceed more than 0.05 wt. % each, and not more than 0.15 wt. % total of the other impurities. Alloy 1 is a conventional 6026 aluminum alloy made without lead called “6026LF.” Alloy 2 is a conventional 6262A aluminum alloy. Alloy 3 is a conventional 6020 aluminum alloy. Alloys 4-11 are new experimental alloys of which alloys 7-9 and 11 are the invention alloys.

The alloys were cast as about 3-inch (ST)×5-inch (LT)×14-inch (L) ingots that were scalped to about 2.5 inches thick and then homogenized. The ingots were then hot rolled to about 0.25-inch gauge plates, corresponding to an approximate 87% reduction. The plates were then solution heat treated and then cold water quenched. The plates were then cut into pieces, which pieces were processed to one of a T6, T8 or T9 temper, as per below:

T6: artificially age at 355° F. (° C.) for 8 hours;

-   -   T8: cold roll to a final gauge of 0.194 inch (about a 22%         reduction) and then artificially age at 355° F. (° C.) for 8         hours;     -   T9: artificially age at 355° F. (° C.) for 8 hours and then cold         roll to a final gauge of 0.194 inch (about a 22% reduction).         The mechanical properties of the pieces were then tested in         accordance with ASTM E8 and B557, the results of which are shown         in Tables 2-4, below. All tests results are relative to the         longitudinal (L) direction.

TABLE 2 Mechanical Properties of Alloys - T6 temper UTS TYS Elong. Alloy Temper (kis) (ksi) (%) 1 (6026LF) T6 48 43.4 13.7 2 (6262A) T6 49 44.2 13.6 3 (6020) T6 51.2 45 14.1 4 T6 51.5 48 12 5 T6 53 50.1 13.4 6 T6 53.3 50.3 13.5 7 T6 49.6 39.8 18.7 8 T6 52.6 42.4 15.8 9 T6 55 48.3 14.5 10 T6 48.9 44.3 15 11 T6 57.2 50.5 13.3

TABLE 3 Mechanical Properties of Alloys - T8 temper UTS TYS Elong. Alloy Temper (kis) (ksi) (%) 1 (6026LF) T8 50.8 49.2 7.9 2 (6262A) T8 48.5 46.5 9.2 3 (6020) T8 48.8 46 8.6 7 T8 51.4 46.4 11.9 8 T8 52.8 49.1 10.9 9 T8 55.9 54.3 8.4 10 T8 50.3 47.9 11.4 11 T8 56.1 52.9 8.6

TABLE 4 Mechanical Properties of Alloys - T9 temper UTS TYS Elong. Alloy Temper (kis) (ksi) (%) 1 (6026LF) T9 54.3 52.5 4.6 2 (6262A) T9 56 53.2 4.4 3 (6020) T9 56.5 53.4 5.4 4 T9 60.3 58.4 4.1 5 T9 62.8 61.2 4.9 6 T9 61.5 60.3 4.6 7 T9 57.7 55.6 7.4 8 T9 62.5 60.6 4.8 9 T9 64.5 63.7 3.8 10 T9 58.2 57.4 4.8 11 T9 66.6 64.1 4.7

As shown, invention alloys 8-9 and 11 realize higher strengths relative to conventional alloys 1-3 and at comparable elongation values. Further, alloy 7 realizes an improved combination of strength and elongation over the conventional alloys. The invention alloys all include high excess silicon levels, which is expected to improve wear resistance. Non-invention alloys 4-6 contained little excess silicon, so their wear resistance may be low. Non-invention alloy 10 had excess magnesium (not silicon), so its wear resistance is expected to be poor. See Table 5, below, and FIG. 1 . The high amounts of Cu+Zn also facilitate solid solution strengthening and may also facilitate corrosion resistance. The use of bismuth additions in favor of tin are expected to improve machinability, to improve crack initiation and fracture toughness under aggressive machining conditions.

TABLE 5 Excess Silicon and Cu + Zn Content (wt. %) Excess (Excess-Si) × Alloy Si Mg Fe* Si** Cu + Zn (Cu + Zn) 1 0.77 0.74 0.44 0.196 0.45 0.0881 2 0.72 0.89 0.48 0.046 0.32 0.0146 3 0.56 1.00 0.39 −0.148 0.61 −0.0902 4 0.72 0.87 0.49 0.054 0.33 0.0178 5 0.87 0.98 0.53 0.127 0.57 0.0724 6 0.92 0.98 0.62 0.147 0.46 0.0677 7 1.12 0.60 0.20 0.707 1.18 0.8338 8 1.14 0.57 0.26 0.724 1.19 0.8615 9 0.95 0.90 0.44 0.283 1.56 0.4419 10 0.62 1.02 0.51 −0.139 0.75 −0.1046 11 2.91 1.38 0.32 2.006 0.42 0.8424 *As noted in U.S. Pat. No. 4,637,842: “It is usual to assume that a percentage of the total Si content equal to ⅓ of the Fe content is lost to the intermetallic compounds.” **Excess silicon is calculated as (Si − (Fe*0.333))) − (Mg/1.73); a negative number means there is excess magnesium instead of silicon.

PANDAT calculations were also completed on various ones of the above alloys at an aging temperature of 340° F. to determine the amount of Mg₂Sn, Mg₂Si, Q, and Al₂Cu phases in those alloys. PANDAT calculations were also completed on a prior art alloy described in European Patent No. EP0828008. Table 6 shows the results.

TABLE 6 PANDAT results - Precipitates Phases (wt. %) Alloy Mg₂Sn Mg₂Si Q Al₂Cu Q + Al2Cu + Mg2Si 2 0.53% — 1.39% — 1.39% 3 0.70% — 1.71% 0.28% 1.99% 4 0.57% — 1.27% 0.05% 1.32% 7 — — 1.25% 1.16% 2.41% 8 0.26% — 1.03% 1.23% 2.26% 9 0.42% — 1.62% 0.59% 2.21% 11  — 0.96% 1.88% — 2.84% Prior Art* 0.56% — 1.53% 0.13% 1.66% *The Prior Art alloy is per Table 1 of EP0828008, which shows an alloy having 1.16 wt. % Si, 0.39 wt. % Fe, 0.45 wt. % Cu, 0.32 wt. % Mn, 0.93 wt. % Mg, 0.042 wt. % Ti, 0.81 wt. % Sn, and 0.45 wt. % Bi, the balance being aluminum and impurities, with ≤0.05 wt. % of any one impurity, and with ≤0.15 wt. % of impurities in total. As shown, invention alloys 7-9 and 11 are predicted to have high amounts of the applicable precipitate phases (Q, Al₂Cu, Mg₂Si) as comparted to the non-invention alloys and the prior art alloy. Moreover, all the non-invention and prior art alloys contained much higher amounts of Mg₂Sn. As the present inventors have recognized, Mg₂Sn may be detrimental to machinability at the applicable machining temperatures and/or machining feed rates. Thus, the invention alloys define novel and inventive aluminum alloys useful in various applications, including, for instance, applications involving extrusion and/or machining.

Example 2—Pilot Scale Testing

Six pilot scale billets (11-inch or 14.75-inch rounds) were produced, the compositions of which are provided in Table 7, below (all values in weight percent).

TABLE 7 Example 2 Alloy Compositions* Alloy Si Fe Cu Mn Mg Cr Zn Ti Sn Bi Alloy 1a  0.74 0.46 0.41 0.56 0.77 0.07 0.02 0.07 0.01 0.89 Alloy 2a  0.79 0.47 0.31 0.03 0.95 0.06 0 0.02 0.74 0.49 Alloy 3a  0.54 0.35 0.71 0.03 0.78 0.065 0.03 0.02 1.08 0 Alloy 8a  1.10 0.25 1.2 0.50 0.55 0.10 0 0.05 0.39 0.36 Alloy 9a  0.90 0.40 0.75 0.10 0.90 0.25 0.73 0.10 0.65 0.60 Alloy 11a 2.80 0.30 0.4 0.15 1.10 0.10 0 0.10 0 1.00 *All alloys contained the listed elements, the balance being aluminum and other impurities, where the other impurities did not exceed more than 0.05 wt. % each, and not more than 0.15 wt. % total of the other impurities. Alloys 1a-3a were cast to correspond to Alloys 1-3 of Example 1, and Alloys 8a-9a and 11a were cast to correspond to Alloys 8-9 and 11 of Example 1, respectively. Alloys 8a-9a, and 11a are invention alloys.

Also, as in Example 1, Alloy 1a is a conventional 6026 aluminum alloy made without lead called “6026LF,” Alloy 2a is a conventional 6262A aluminum alloy, and Alloy 3a is a conventional 6020 aluminum alloy.

After casting, the alloys were homogenized, extruded to into rods (0.587 inch or 0.637 inch), solution heat treated or press-quenched, and then processed to a T8 or T9 temper, as provided in Table 8, below. The T8 materials were solution heat treated (“SHT”), cold drawn, and then artificially aged. The T9 materials were solution heat treated (“SHT”) or press quenched (“PQ”), artificially aged and then cold drawn to the final diameter. All alloys were aged at 350° F. for 8 hours as the artificial aging practice.

TABLE 8 Example 2 Alloy Processing Cold Press- Drawing Quench Re- Extruded or duction Billet Rod Solution of Final Diameter Diameter Heat Area Diameter Alloy (inch) (inch) Treat? (%) (inch) Temper Alloy 11 0.637 PQ 22% 0.562 T9 1a-T9  Alloy 14.75 0.637 PQ 22% 0.562 T9 2a-T9  Alloy 11 0.587 SHT 33% 0.480 T8 3a-T8  Alloy 11 0.637 SHT 22% 0.563 T8 8a-T8  Alloy 11 0.637 SHT 22% 0.563 T8 9a-T8  Alloy 11 0.637 SHT 10% 0.604 T8 11a-T8 Alloy 11 0.637 SHT 22% 0.563 T9 8a-T9  Alloy 11 0.637 SHT 22% 0.563 T9 9a-T9  Alloy 11 0.637 SHT 10% 0.604 T9 11a-T9

After processing, the mechanical properties of the alloys were tested in accordance with ASTM E8 and B557, the results of which are shown in Table 9, below. All tests results are relative to the longitudinal (L) direction. Strength values are in units of ksi. Elongation values are in units of percent (%). The reported values are averages of at least four specimens. (UTS=ultimate tensile strength; YS=tensile yield strength.)

TABLE 9 Example 2 Alloy Mechanical Properties T8 Temper T9 Temper Alloy UTS YS Elong. UTS YS Elong. Alloy 1a  N/A 57.2 55.3 9.0 Alloy 2a  N/A 56.8 55.3 6.3 Alloy 3a  47.4 44.6 17.2 N/A Alloy 8a  57.1 54.8 9.7 65.5 63.7 5.7 Alloy 9a  55.1 53.5 9.7 61.4 59.3 6.0 Alloy 11a 51.8 48.2 10 60.8 58.6 5.0

As in Example 1, the invention alloys 8-9 and 11 realize higher strengths relative to conventional alloys 1-3 and at comparable elongation values. The invention alloys all include high excess silicon levels, which is expected to improve wear resistance. See Table 10, below. The high amounts of Cu+Zn also facilitate solid solution strengthening and may also facilitate corrosion resistance. The use of bismuth additions in favor of tin are expected to improve machinability, to improve crack initiation and fracture toughness under aggressive machining conditions.

TABLE 10 Excess Silicon and Cu + Zn Content (wt. %) Excess (Excess-Si) × Alloy Si Mg Fe Si Cu + Zn (Cu + Zn) Alloy 1a  0.74 0.77 0.46 0.142 0.43 0.06095 Alloy 2a  0.79 0.95 0.47 0.084 0.31 0.02615 Alloy 3a  0.54 0.78 0.35 −0.027 0.74 −0.02029 Alloy 8a  1.10 0.55 0.25 0.699 1.20 0.83860 Alloy 9a  0.90 0.90 0.40 0.247 1.48 0.36492 Alloy 11a 2.80 1.10 0.30 2.064 0.40 0.82570

The machinability of the Example 2 alloys was also tested. Specifically, the T8 and T9 temper alloys were machined per the conditions shown in Table 11, below. The results are shown in Tables 12-13, below, and in FIGS. 2-3 .

TABLE 11 Machinability Conditions Machining Surface Velocity Feed/Rev* Depth per Condition No. (feet per minute) (inch) Pass (inch) 1 600 0.01 0.01 2 600 0.01 0.1 3 200 0.01 0.1 4 100 0.01 0.1 5 600 0.005 0.1 6 100 0.01 0.01 *Feed/Rev = cutting tool feeding distance per revolution (see FIG. 6)

TABLE 12 Machinability Test Results - T8 Temper Machining Mass Number Chips per Alloy Condition No. (grams) of Chips Gram Alloy 3a-T8 1 1.61 138 85.71 Alloy 3a-T8 2 1.65 72 43.64 Alloy 3a-T8 3 2.2 157 71.36 Alloy 3a-T8 4 2.03 56 27.59 Alloy 3a-T8 5 2.17 189 87.10 Alloy 3a-T8 6 1.91 117 61.26 Alloy 8a-T8 1 1.17 84 71.79 Alloy 8a-T8 2 2.03 161 79.31 Alloy 8a-T8 3 1.51 167 110.60 Alloy 8a-T8 4 1.79 179 100.00 Alloy 8a-T8 5 1.65 230 139.39 Alloy 8a-T8 6 1.35 83 61.48 Alloy 9a-T8 1 1.75 192 109.71 Alloy 9a-T8 2 2.2 108 49.09 Alloy 9a-T8 3 1.71 94 54.97 Alloy 9a-T8 4 1.71 111 64.91 Alloy 9a-T8 5 1.54 223 144.81 Alloy 9a-T8 6 1.59 132 83.02 Alloy 11a-T8 1 2.03 61 30.05 Alloy 11a-T8 2 3.06 155 50.65 Alloy 11a-T8 3 2.37 167 70.46 Alloy 11a-T8 4 2.08 142 68.27 Alloy 11a-T8 5 2.3 291 126.52 Alloy 11a-T8 6 1.44 132 91.67

TABLE 13 Machinability Test Results - T9 Temper Machining Mass Number Chips per Alloy Condition No. (grams) of Chips Gram Alloy 1a-T9 1 1.87 173 92.51 Alloy 1a-T9 2 3.86 178 46.11 Alloy 1a-T9 3 2.67 113 42.32 Alloy 1a-T9 4 3.41 89 26.10 Alloy 1a-T9 5 2.28 181 79.39 Alloy 1a-T9 6 1.98 133 67.17 Alloy 2a-T9 1 1.51 203 134.44 Alloy 2a-T9 2 2.93 132 45.05 Alloy 2a-T9 3 2.29 136 59.39 Alloy 2a-T9 4 3.1 130 41.94 Alloy 2a-T9 5 2.33 282 121.03 Alloy 2a-T9 6 1.76 178 101.14 Alloy 8a-T9 1 1.12 98 87.50 Alloy 8a-T9 2 1.06 124 116.98 Alloy 8a-T9 3 1.01 88 87.13 Alloy 8a-T9 4 1.86 137 73.66 Alloy 8a-T9 5 1.51 244 161.59 Alloy 8a-T9 6 1.63 209 128.22 Alloy 9a-T9 1 1.14 121 106.14 Alloy 9a-T9 2 1.71 161 94.15 Alloy 9a-T9 3 1.6 133 83.13 Alloy 9a-T9 4 2.53 194 76.68 Alloy 9a-T9 5 1.77 275 155.37 Alloy 9a-T9 6 1.08 143 132.41 Alloy 11a-T9 1 1.24 118 95.16 Alloy 11a-T9 2 1.46 119 81.51 Alloy 11a-T9 3 1.95 128 65.64 Alloy 11a-T9 4 2.36 110 46.61 Alloy 11a-T9 5 1.54 209 135.71 Alloy 11a-T9 6 1.72 322 187.21

As shown, despite being substantially stronger than Alloys 1a-3a, invention alloys 8a-9a, and 11a achieve comparable if not better machinability results at various Machining Conditions. For instance, for Machinability Condition No. 1, Alloy 9 in the T8 temper realized 28% more chips than conventional Alloy 3a in the T8 temper (109.71 versus 85.71 chips per gram yields a ratio of 1.28 or a 28% improvement). For Machinability Condition No. 2, all alloys achieve better machinability, with Alloy 8 in the T8 temper realizing 82% more chips than conventional Alloy 3a in the T8 temper (79.31 versus 50.65 chips per gram yields a ratio of 1.82 or an 82% improvement). Similar results are shown for Machinability Conditions 3-6 for alloys in the T8 temper as well Machinability Conditions 1-6 for alloys in the T9 temper. Thus, the invention alloys may realize an improved combination of strength and machinability.

Wear testing was also conducted on various ones of the Example 2 alloys as per the “Wear Testing Procedure,” provided below, in both the bare (unanodized) and anodized conditions. The results are provided in Table 14 below and FIGS. 4-5 . The average is of three specimens with the standard deviation also provided.

Average Average (±std.dev) (±std.dev) weight loss weight loss Alloy-Temper (mg) (Bare) (mg) (Anodized) Alloy 3a-T8 19.3 ± 2.1 2.8 ± 0.4 Alloy 8a-T8 22.4 ± 3.0 3.8 ± 0.5 Alloy 9a-T8 24.6 ± 1.2 2.6 ± 0.2 Alloy 11a-T8 18.3 ± 0.3 4.3 ± 0.1 Alloy 1a-T9 20.7 ± 0.9 3.5 ± 0.2 Alloy 2a-T9 22.6 ± 2.1 3.0 ± 0.2 Alloy 8a-T9 24.8 ± 0.5 3.4 ± 0.3 Alloy 9a-T9 22.4 ± 3.5 3.1 ± 0.1

As shown, the invention alloys (8a-9a, 11a) realize at least comparable wear resistance to the conventional alloys (1a-3a).

Wear Testing Procedure

Oscillating linear dry sliding wear tests were performed using a TABER® Linear Abraser Model 5750 to determine the wear index of bare aluminum¹ and a Type III anodized hard coat aluminum² (per MIL-A-8625F). A load of 750 grams was applied to the abradant (¼ inch diameter CS-17 WEARASER®). Testing was conducted at 60 cycles per minute using a 4-inch stroke length for 10,000 cycles. Refacing of the abradant was performed for 10 cycles with a 350 gram load on an S14 brand refacing strip before testing and after every 1000 cycles. The sample specimens were 6″ long and approximately 0.5″ wide. Specimens were placed in a desiccator prior to and following testing to establish constant weight in lieu of the conditioning specified in ASTM D 4060. Weight loss was measured after every 10,000 cycles. Three replicates were tested for each condition.

Notes:

-   -   1. The as-machined bare sample surfaces had an average (±std.         dev) roughness (Sa) of 31.8±5.1 On (microinches).     -   2. The anodizing process comprises cleaning in Bonderite 4215 at         150° F. for 5 minutes followed by sulfuric acid anodizing at         34° F. with an acid concentration of 188 g/L using the following         sequence: 10 A/sq. ft. for 10 minutes, 5 minute ramp to 36 A/sq.         ft and hold for 25 minutes. DI (deionized) water rinsing         followed both steps and the samples were oven dried at 180° F.

End of Wear Test Procedure.

While a number of embodiments of the present invention have been described, it is understood that these embodiments are illustrative only, and not restrictive, and that many modifications may become apparent to those of ordinary skill in the art. Further still, unless the context clearly requires otherwise, the various steps may be carried out in any desired order, and any applicable steps may be added and/or eliminated. 

What is claimed is:
 1. An aluminum alloy comprising: from 0.50 to 3.0 wt. % of X, wherein X comprises (wt. % Bi+wt. % Sn); from 0.50 to 4.0 wt. % Si; from 0.30 to 2.5 wt. % Mg; wherein the aluminum alloy comprises at least 0.20 wt. % excess silicon; from 0.25 to 1.5 wt. % Cu; up to 2.0 wt. % Zn; from 0.05 to 1.5 wt. % Mn; up to 0.70 wt. % Fe; up to 0.35 wt. % of Cr; up to 0.25 wt. % each of Zr and V; up to 0.15 wt. % Ti; the balance being aluminum, optional incidental elements and impurities; wherein the aluminum alloy comprises at least 1.75 mol. % of Y, wherein Y is (mol. % Q-phase+mol. % Al₂Cu+mol. % Mg₂Si) as calculated using PANDAT and a temperature of 340° F.
 2. The aluminum alloy of claim 1, comprising not greater than 0.4 wt. % Sn.
 3. The aluminum alloy of claim 1, comprising not greater than 0.01 wt. % Sn.
 4. The aluminum alloy of claim 3, comprising from 0.4 to 1.2 wt. % Bi.
 5. The aluminum alloy of claim 1, comprising at least 0.30 wt. % excess silicon, wherein excess silicon is calculated from the formula ((wt. % Si)−((wt. % Fe)*0.333))−((wt. % Mg)/1.73).
 6. The aluminum alloy of claim 5, comprising at least 0.70 wt. % Si.
 7. The aluminum alloy of claim 6, comprising at least 0.40 wt. % Mg.
 8. The aluminum alloy of claim 7, comprising at least 0.35 wt. % Cu.
 9. The aluminum alloy of claim 8, comprising from 0.20 to 1.0 wt. % Zn
 10. The aluminum alloy of claim 9, comprising from 0.10 to 0.5 wt. % Fe.
 11. The aluminum alloy of claim 10, comprising from 0.10 to 0.60 wt. % Mn
 12. The aluminum alloy of claim 11, comprising from 0.02 to 0.12 wt. % Ti.
 13. The aluminum alloy of claim 12, wherein strontium is included in the aluminum alloy as an impurity.
 14. The aluminum alloy of claim 1, wherein X is selected from the group consisting of Bi, Sn and mixtures thereof, and wherein indium is included in the aluminum alloy as an impurity, and wherein the aluminum alloy comprises less than 0.04 wt. % In.
 15. An aluminum alloy comprising: from 0.65 to 1.15 wt. % of X, wherein X is selected from the group consisting of Bi, Sn, In, and combinations thereof; from 0.95 to 1.3 wt. % Si; from 0.45 to 0.70 wt. % Mg; wherein the aluminum alloy comprises at least 0.30 wt. % excess silicon, wherein excess silicon is calculated from the formula ((wt. % Si)−((wt. % Fe)*0.333))−((wt. % Mg)/1.73); from 1.0 to 1.4 wt. % Cu; up to 1.0 wt. % Zn; up to 1.5 wt. % Mn; up to 0.70 wt. % Fe; up to 0.35 wt. % of Cr; up to 0.25 wt. % each of Zr and V; up to 0.15 wt. % Ti; the balance being aluminum, optional incidental elements and impurities; wherein the aluminum alloy comprises at least 2.0 mol. % of Y, wherein Y is (mol. % Q-phase+mol. % Al₂Cu+mol. % Mg₂Si) as calculated using PANDAT and a temperature of 340° F.
 16. An aluminum alloy comprising: from 0.5 to 1.4 wt. % of X, wherein X is selected from the group consisting of Bi, Sn, In, and combinations thereof; from 2.2 to 3.5 wt. % Si; from 1.1 to 2.5 wt. % Mg; wherein the aluminum alloy comprises at least 0.50 wt. % excess silicon, wherein excess silicon is calculated from the formula ((wt. % Si)−((wt. % Fe)*0.333))−((wt. % Mg)/1.73); up to 1.5 wt. % Cu; up to 2.0 wt. % Zn; up to 1.5 wt. % Mn; up to 0.70 wt. % Fe; up to 0.35 wt. % of Cr; up to 0.25 wt. % each of Zr and V; up to 0.15 wt. % Ti; the balance being aluminum, optional incidental elements and impurities. 